The objective of this study is to examine the effects of exposure to prevalent insecticides on neurobehavioral outcomes in a cohort of 399 children. We will include an evaluation of prenatal exposure effects observed during the newborn period, as well as postnatal exposure effects through age six. Children are currently enrolled in cohort study investigating the health, developmental, and behavioral consequences of exposure to a variety of environmental toxicants and with planned follow-up to age two. Original funding was through NIEHS/EPA. Biological samples will be used to assess exposure to insecticides prenatally (maternal urine, infant meconium) and postnatally (child urine). We will examine newborn neurobehavioral outcomes within the first 36 hours of life and during a home visit at 4 weeks, using the Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS), to assess the earliest effects of prenatal exposure to prevalent insecticides. The study will extend follow-up of this cohort to include assessments or development, cognition, motor skills, and behaviors at ages 4, 5, and 6 in an effort to examine the effects of postnatal exposure to insecticides. Analyses will employ multivariate and causal modeling techniques. Potential covariates will include maternal drug and alcohol use during pregnancy, pregnancy outcomes and infant characteristics, maternal characteristics and qualities of the home environment, socioeconomic status variables, lead and tobacco exposure, and other variables as appropriate. Data from biological samples and neurobehavioral testing collected at earlier visits will also be available. We propose the following aims: AIM 1 To characterize the association of prenatal exposure to prevalent insecticides, as determined by biomarkers collected in maternal urine during pregnancy and in meconium shortly after birth, with neurobehavior during the newborn period measured with the NNNS. Aim 2 To characterize the association of postnatal exposure to prevalent insecticides, as determined by measures of insecticides in child urine with neurobehavior at ages four to six years. We will carefully examine the effects of prenatal and postnatal exposure to prevalent insecticides using multiple biological markers of exposure at numerous time points and sensitive neurobehavioral assessment tools from the newborn period through age five years. This study offers a unique opportunity to examine the early effects of prenatal and postnatal exposure to insecticides on neurobehavioral outcomes in a trajectory from the newborn period through age six years, while utilizing the research infrastructure of an established cohort study.